My Mechanic Is Stumped – Please Provide Any Suggestions

[WausauFLA]

Hi, My name is Cliff and I am a 1998 Corolla owner (aka: Chevy Prizm) from Northwest Florida.

My mechanic is making no headway and is getting ready to throw in the towel on my Corolla. The car stalls when headlights or AC is turned on – the car runs fine otherwise. For a few weeks prior to this, the headlights would never turn off if they were ever turned on initially via the headlight switch– I would have to pull a relay under the hood momentarily and plug it back in to extinguish the lights. During this period, the Daytime Running Lights became totally inoperative (meaning that they never came on, but had always worked previously). Immediately prior to this, the car had been in the shop because it would not start and run unless one of the turn signals was on – this was the initial problem that seems to be linked to the other two problems. Prior to all this, the car had zero problems ever since I bought it new.

Any suggestions on this problem that I can pass along to my mechanic?

Thanks.

[retiredat44]

You may have a Vacuum leak in one of the switches that enable the idle up with a/c or lights on !

I know you have fuel injection, but believe you still have some of the idle up components shared with all corollas that cause idle up with a/c and/or lights turned on.. it has an 'idle up' circuit.


I am very interested in the lights switched on and idle up myself. I while back immediately after I rebuilt my carburetor the idle up with the lights on stopped working. for the life of my I cannot figure out what I messed up. The A/C idle up still work great.

There are idle up vacuum lines and switches on the firewall with the vacuum lines running to them. It is sort of a boolean type operation where a combination of vacuum lines opened by the lights enable a small bit of air to enter through these switches allowing the idle to increase a small amount. The a/c has a vacuum line that goes to the firewall ont he passenger side and a metal vacuum switch on the back, under the carburetor that pulled a diaphram that in turn pull some linkage which turns the idle up. This is on the passenger side of the carb.

Since your problem lies with both a/c and lights not enabling the the idle up, it is at a common point with both.

I am intrerested in seeing your solution.


BTW, since mine in a 1989 Corolla, and yours is much newer, I can only assume you have the same idle-up stuff, but you have additional parts mine doe snot have since yours has Fuel Injection instead of a carb. Yours has a idle control valve my carb model does not. It is called Idle Air Control Valve.

[Bitter]

it sounds like you initially had a short to power in your headlights, and i suspect that you have damage to the main engine wiring harness. remove the wrapping and inspect the wires carefully, there could be burnt, pinched, or cut wires which are shorting together and causing the symptoms.

[robert1967az]

I had the same problem. After two days of troubleshooting I took it to my mechanic. It took him a week, tracing and thinking between other jobs, to find the solution: Running light relay module. Under the dash, not a ice cube relay, a module assembly. Part 94859202. I also has a bad ground on the jumper for the main wiring harness. $357.00 Hope this saves all of you some cash.